The metabolic intermediate responsible for the hematological toxicity of benzene is unknown. Our overall hypothesis is that muconaldehyde is an intermediate of benzene metabolism which plays a role in the resultant hematotoxicity. In order to preliminarily study this hypothesis we propose: 1. To synthesize the three-geometrical isomers of muconaldehyde, i.e. trans, trans-, cis, trans-, and cis, cis-muconaldehyde, and unequivocally establish their structures using physical methods. 2. To apply chemical and analytical techniques for the recovery of muconaldehyde from biological systems, including determining solubility and stability in these systems. 3. To determine whether muconaldehyde is formed from benzene in an in vitro mouse liver microsome system. 4. To evaluate the toxicity of muconaldehyde by: a. ascertaining its effects on the growth characteristics of human erythropoietic precursor cells in a plasma clot culture system. b. administering muconaldehyde to CD-1 mice and evaluating these animals for hematotoxicity. c. studying whether it is mutagenic in bacteria and preliminarily assessing its ability to interact with DNA in model systems.